There are several kinds of exterior insulating sheathings existing: Polystyrene, polyurethane, polyisocyanurate, glass fiber, and phenolic sheathings are known and used. These are normally 4 feet wide by 8 feet long or 4.times.9, and occasionally 2 feet by 8 feet. However, these do not possess the rigidity one would wish them to have.
In house construction, generally walls are built on the floor: The beams are laid down and the sheathing fixed to them, after which the wall is lifted to an upright position: In Canada, walls that are constructed on the floor and then upraised, is termed platform construction. The insulating sheathings are normally 4 feet by 8 feet. In order to fix the insulating sheathing one has to walk on the 2".times.6" or 2".times.4" beams, or beams having other size, sometimes walking on the sheathing itself. Such walking on the sheathing often results in its perforation due to its weakness. Another problem associated with some sheathings is their tendency to warp, yielding a surface which is not flat, in particular the glass fiber one. In such cases, new sheathing must replace the old one. Because sheathings of glass fiber and foam have low strength, braces have also to be put; this is an additional expense and adds to costs. Also, there is no composite materials having exterior insulating sheathing that exist. The composite materials that are known, are generally spot glued.